1. Field of the Invention
This invention relates to a system for controlling the flow of water from a basin for retaining water.
2. Description of the Related Art
When runoff of water has the potential for damaging property, grading of land from which the water runs is often done in order to direct the water into a reservoir for temporary storage.
Such reservoirs are called by various names. Some of these are debris basin, containment basin, detention basin, and retention pond.
The size of the reservoir is determined by several factors, such as expected precipitation, the total area upon which such precipitation may fall, the percentage of moisture which will be absorbed by the soil, and the rate at which water may be released from the reservoir.
Usually regulatory authorities establish a given volume of water per unit of time that may flow through the stream or channel which carries the water that leaves the reservoir. For convenience, such stream or channel will, for the purposes of this patent application, be termed the “outflow channel.”
Traditionally these reservoirs use orifice-type outlet controls that discharge increased flows under increased water pressure (head). Basically, a reservoir outlet aperture exists in the containment wall of the reservoir, usually near the bottom of the reservoir, through which the discharged water can flow. The higher the level of the water in the reservoir, the greater will be the water pressure at the reservoir outlet aperture; and, consequently, the greater will be the volume of water per unit of time which flows through the aperture.
In order to assure that the maximum permissible volume of water per unit time flowing through the outflow channel is never exceeded, the size of the reservoir outlet aperture is selected so that only this volume of water will flow through the reservoir outlet aperture when the water in the reservoir is at its highest level.
This necessarily means that when the level of water in the reservoir is below its maximum level, the flow through the reservoir outlet aperture will be less than the regulatory authority permits. Indeed, the lower the level of water in the reservoir, the less will be the volume of water per unit of time that flows through the reservoir outlet aperture.
Because the maximum flow through the outflow channel will occur only for the time when the level of water in the reservoir is at its highest position, the volume of the reservoir must be greater than it would have to be if the maximum flow through the outflow channel could occur for a longer period of time.
Of course, a larger reservoir requires more land and costs more money to construct.
The Red Valve Company, Inc. of Carnegie, Pa., has manufactured and marketed a line of valves under the trademarked name TIDEFLEX, which valves allow water to flow from the valves only when the upstream pressure is greater than the downstream pressure. The valves have a duckbill shape that precludes water from flowing in a reverse direction, i.e., they constitute check valves for the water. Such valves are most often utilized where water under pressure is to be discharged into other water below the surface of such other water.
The Red Valve Company, Inc. owns U.S. Pat. No. 4,268,005 which covers a “pinch valve” that has a sleeve inside a conduit with valves to pump a fluid between the sleeve and that conduit in order to collapse the sleeve partially or completely and thereby restrict the flow of liquid through the sleeve. No use was, however, suggested for the sleeve other than its employment within the conduit; and, when collapsed, the pinch valve has three arms projecting from a central location, rather than a flat duckbill.